Scanning Electrochemical Microscopy Under Forced Convection

In the present contribution, two approaches of hydrodynamic electrochemical systems are discussed in the context of scanning electrochemical microscopy (SIECM) The first approach termites a high-precision stirring device into the experimental setup. The second way is based on a special flow cell configuration, which is adapted to SECM measuring requirements. In both cases, well-defined convective mass transport could be established resulting in steady state diffusion layer characteristics in the vicinity of large substrate electrodes operated under chronoamperometric measuring conditions. For a range of rotation frequencies (approach 1) or flow rates (approach 2) the thickness and the stability of the diffusion layer was studied by hydrodynamic SECM in the substrate generation / tip collection (SG/TC) as well as in the competition mode using ferrocene methanol as redox mediator. The reproducibility of corresponding hydrodynamic SECM experiments was much better than in quiescent solution In addition, preliminary studies of gas evolution were undertaken applying hydrodynamic SECM. In particular, hydrodynamic SECM in the SGITC mode based on in-situ generation of hydrogen was found very attractive for a wide tango of applications.